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Asthma: causes and symptoms

This cross-section shows how asthma affects the airway muscles and wall

This module covers the causes, triggers and effects of this common condition

Update Module1802
From this module you will learn:
  • How common asthma is and what symptoms patients present with
  • How the inflammatory response occurs and what triggers this
  • The long-term causes of asthma
  • Other conditions that can be mistaken for asthma

Download this module - this includes the 5 minute test - here.

Asthma is an extremely common condition. Around 5.4 million people have been diagnosed with it in the UK – more than one in every 12 individuals. Although asthma can be controlled, people still die from this condition every year, with more than 1,200 deaths in 2014 attributed to it.

If all patients used an appropriate treatment correctly, it is estimated that 90% of these deaths would be prevented. To help prevent symptoms, exacerbations and deaths from occurring from asthma, pharmacists must therefore ensure patients use their medicines appropriately so they get the most from their treatment.

What is asthma?

Asthma is an inflammatory disease of the airways. This inflammation occurs in response to stimuli, which leads to an airflow obstruction. It is a chronic condition that currently has no cure. However, asthma can be managed with treatment.

The airways are made up of a central trachea (windpipe) that branches off into tubes called bronchi. These split further into bronchioles, which lead to the alveoli, where gas exchange occurs during breathing. When asthma flares up, inflammation occurs due to hyper-reactivity to a stimuli – which can be internal or external. The airways then swell, narrow and the airway muscles contract, leading to a restriction in breathing.

In this inflamed state, the lungs also produce greater quantities of mucous, which leads to a clogging up of the airways – further limiting the movement of air and causing an individual to cough in an effort to unblock them.

Causes of asthma

Asthma can occur at any age, although patients tend to develop the condition in early childhood.

There is no single cause, but there are many factors that can influence the likelihood of developing the condition. For example if:

  • a patient has other atopic conditions, eg eczema, hayfever or allergies
  • a patient has a first-degree relative with an atopic condition – including asthma
  • they were born prematurely
  • their mother smoked during pregnancy
  • they were exposed to cigarette smoke as a child
  • they were exposed to certain chemicals sometimes found in the workplace.
Preventing asthma

Although some of the factors above cannot be influenced, there is advice that pharmacists can provide to help reduce the risk of asthma in the wider population:

  • recommend that mothers breastfeed
  • explain the risks to parents of smoking around their children; stress that they cannot see all the smoke produced by cigarettes and that unseen smoke can be doing damage
  • recommend that mothers-to-be do not smoke during their pregnancy
  • explain the risk of exposure to chemicals in
  • the workplace and advise patients to discuss any concerns about their working conditions or standard operating procedures with their employer.

Many believe that air pollution, the use of chlorine in swimming pools and changing hygiene standards (see box 1: Hygiene hypothesis) are also thought to play a role.

What triggers asthma?

For those who have asthma, there are a variety of triggers – stimuli that can cause the condition to flare up. Every individual will have their own set of triggers and being able to identify these means you can then recommend ways to avoid them. Examples of triggers and methods of controlling symptoms include:

Pathogen exposure – some individuals find their asthma symptoms flare up when they have a cold or the flu. If a patient has these infections, you should advise them to take their reliever inhaler regularly to prevent the symptoms of asthma from occurring.

Medicine use – NSAIDs (non-steroidal anti-inflammatory drugs) can lead to bronchospasm – muscle spasm of the bronchiole – in roughly 5% of asthmatics. In addition, aspirin, propranolol and recreational drugs are known triggers.

If a patient has been prescribed either of the first two, you can suggest they speak to the prescriber to seek out an alternative. If the item has been bought over the counter – eg ibuprofen – you can recommend an alternative method of pain relief.

Climate – atmospheric conditions such as moving from cold to hot, poor air quality, humid environments or pollen exposure can all be triggers.

As there are many different environmental factors that can contribute to a flare-up, you should recommend that if a patient knows an environment will exacerbate their asthma, they should use their reliever inhaler before they step out the door. For example, if a patient is aware they have to leave the warm house to go to a cold environment, they should use their inhaler before they leave.

Exercise – patients whose asthma is exercise-induced should be advised to use their reliever inhaler prior to undertaking these activities.

Home conditions – mould or damp, house dust mites, chemicals in cleaning products, animal fur or feathers can all be triggers. Patients should ensure their home is clean of mould and damp and avoid using chemical products that exacerbate their condition.

Having a wooden floor can help prevent animal fur or dust building. Doing a hot wash can help remove dust mites present on bed linens and clothing, as can steam-cleaning sofas and mattresses.

Smoke – cigarette smoking, secondhand smoke and fire smoke act as triggers and should all be avoided where possible.

Food allergies – these can trigger an exacerbation and there is a huge range of options. Keeping a food diary of when asthma symptoms occur can help determine if a certain ingredient is responsible. Once it has been determined that a food – for example, peanuts – causes a reaction, you should advise your patient to avoid it.

Emotion – stress, anxiety or hormone fluctuations can all have an effect. You should recommend techniques that patients can adopt to avoid stress or anxiety.

What happens during an asthma exacerbation?

An exacerbation involves the body going through a series of reactions, from initial exposure to airway closure:

  1.     The allergen/trigger comes into contact with airway cells
  2.     Chemicals such as histamine and other inflammatory medications are released at that site
  3.     Some of these chemicals cause a widespread constriction of the bronchiole muscle
  4.     This leads to a further release of inflammatory mediators
  5.     The release of proteins – including toxic proteins – is triggered
  6.     Some of these proteins damage the epithelium (outer tissue of lungs), leading to a greater exposure to irritants and provoking further inflammation.
Symptoms of asthma

When the inflammatory process is under way, there is a noticeable change in the airways as they swell and narrow, and mucous production increases. There are a variety of symptoms a sufferer may show, including:

  • a consistent wheeze or whistle when breathing, due to the narrowing of the airways
  • shortness of breath – due to a restricted entry and exit of air, making the patient feel their breathing is laboured
  • a tight chest – often described as restriction in the amount of air an individual can inhale
  • coughing – caused by a build-up of mucous in the inflamed airways; this is an involuntary response to try to remove the blockage and return breathing to normal
  • night-time coughing – a common occurrence in asthma exacerbations. This can lead to a disturbed night’s sleep, and fatigue the following day.
What happens during an asthma attack?

An asthma attack is said to be occurring if a patient’s:

  • reliever is no longer helping
  • symptoms are getting worse
  • breathing is becoming more difficult.

If one of your patients experiences a severe asthma attack, you should refer them immediately to hospital. Emphasise the importance of taking their medicines with them to the hospital, as this will help staff decide on appropriate treatment.

If a patient asks for advice about what to do when they suffer an attack, you can suggest Asthma UK's recommendation that they sit upright rather than lying down and use their reliever inhaler once a minute, for a maximum of 10 minutes. If the 10 puffs do not help their symptoms, and they are using their inhaler correctly, they should visit a hospital.

If a patient has an asthma attack and manages to control it without seeking medical help, they may feel the problem has been overcome. However, you should recommend they make an appointment to see their GP soon, as their prescribed dosing regimen may need to change to prevent future attacks and get their asthma under control.

This referral is important, as one in six people who have an asthma attack will require hospital care within two weeks.

Is the cough definitely asthma?

A cold is commonly accompanied by a cough, but this is usually not confused with asthma due to its limited duration and other accompanying symptoms. However, there are other conditions that can cause a persistent cough, which may be mistaken for asthma:

Allergy-related cough – these coughs are usually non-productive – they do not bring up mucous or sputum – and tend to be worse at night. This symptom rarely occurs in isolation, and patients often suffer from a runny nose, sneezing and itchy eyes. For example, a persistent cough is a typical symptom associated with hayfever.

ACE (angiotensin converting enzyme) inhibitors – a common side effect of this drug class is a persistent dry cough that can disturb sleep. This affects one in 10 men and one in five women. If someone has this side effect, a suitable alternative such as an ARB (angiotensin receptor blocker), which does not have this side effect, can be recommended.

Post-nasal drip – this is characterised by a nasal discharge of mucous that flows down the throat, and triggers the individual to clear their throat and cough. Asking patients if they are currently suffering from any nasal symptoms may help to rule this out as a cause.

Gastro-oesophageal reflux disease – is a common cause of persistent cough. It is most common at nights, after meals or when a patient is lying down.

Diagnosing asthma

When a patient offers you a description of their symptoms, it may be clear that they have asthma. However, there are a variety of tests that help in diagnosing this condition and deciding upon a suitable treatment.

Peak flow – a peak flow meter measures how quickly a patient can blow the air out of their lungs. Patients not accustomed to using this meter may take several attempts to master the correct technique. If you show the patient how to use their meter in your pharmacy, it is essential they leave knowing how to use it correctly, as their future treatment may depend on the results they generate.

Peak flow meters are often given out on prescription and patients are encouraged to take readings over a period of weeks – either with or without a newly prescribed medication.

Spirometry – this is used to help assess lung function. A spirometer measures the forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC). The FEV1 is how much air a patient can force out of their lungs in one second, whereas the FVC is how much air in total an individual can exhale during a forced breath.

These tests help monitor the severity of a patient’s condition – by demonstrating restriction in airflow – and how they are responding to treatment. This test is usually carried out at home by the patient, who will be supplied with the spirometer.

Other tests include recording how airways react in the presence of a trigger and testing inflammation levels, by either taking a mucous sample or testing nitric oxide concentration.

This module has focused on how to recognise the causes and symptoms of asthma, and how the condition is diagnosed. A second module, focusing on the treatments available to asthmatics, will be published on September 17.

Box 1: Hygiene hypothesis

This theory is one explanation for the increased cases of autoimmune and allergic diseases seen in the modern world.

In general, there has been a decrease in incidences of infection in western society. This is due to both a more hygienic way of life, and the introduction of antibiotics and routine vaccinations.

It is believed that this deficit of external infectious stimuli leads to the body’s natural defence – the immune system – overreacting in the presence of a typically non-invasive stimulus. Reaction can result in the symptoms associated with asthma or allergies.

However, the name of the hypothesis is slightly misleading as it is not true that being generally hygienic causes this condition. Rather, it is the systematic improvements in techniques to destroy and remove pathogens that is preventing their exposure. This is one explanation for the fact that developing countries have fewer incidences of allergies compared to the developed world.

Asthma causes and symptoms CPD

Reflect What is the hygiene hypothesis? How can patients avoid common asthma triggers? What occurs in the body during an asthma attack?

Plan This article describes the causes and symptoms of asthma and includes information about how the inflammatory response occurs, and common triggers associated with the condition. Other conditions that can be mistaken for asthma are also discussed.

Act Read more about asthma on the NHS Choices website.

Find out more about respiratory allergies from the Allergy UK website.

Read more about triggers for asthma such as pollution, food, stress and exercise on the Asthma UK website.

Find out about support groups and reliable sources of information for patients with asthma. Identify any patients who might benefit from a patient consultation or medicine use review.

Evaluate Are you now confident in your knowledge of the causes and symptoms of asthma? Could you give advice to patients about avoiding common asthma triggers?

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